2,299 research outputs found
Fano regime of transport through open quantum dots
We analyze a quantum dot strongly coupled to the conducting leads via quantum point contacts - Fano regime of transport - and report a variety of resonant states which demonstrate the dominance of the interacting resonances in the scattering process in a low confining potential. There are resonant states similar to the eigenstates of the isolated dot, whose widths increase with increasing the coupling strength to the environment, and hybrid resonant states. The last ones are approximatively obtained as a linear combination of eigenstates with the same parity in the lateral direction, and the corresponding resonances show the phenomena of resonance trapping or level repulsion. The existence of the hybrid modes suggests that the open quantum dot behaves in the Fano regime like an artificial molecule
On Eisenbud's and Wigner's R-matrix: A general approach
The main objective of this paper is to give a rigorous treatment of Wigner's and Eisenbud's R-matrix method for scattering matrices of scattering systems consisting of two selfadjoint extensions of the same symmetric operator with finite deficiency indices. In the framework of boundary triplets and associated Weyl functions an abstract generalization of the R-matrix method is developed and the results are applied to Schrödinger operators on the real axis
An experiment for the measurement of the bound-beta decay of the free neutron
The hyperfine-state population of hydrogen after the bound-beta decay of the
neutron directly yields the neutrino left-handedness or a possible right-handed
admixture and possible small scalar and tensor contributions to the weak force.
Using the through-going beam tube of a high-flux reactor, a background free
hydrogen rate of ca. 3 s can be obtained. The detection of the neutral
hydrogen atoms and the analysis of the hyperfine states is accomplished by Lamb
shift source type quenching and subsequent ionization. The constraints on the
neutrino helicity and the scalar and tensor coupling constants of weak
interaction can be improved by a factor of ten.Comment: 9 pages, 5 figures. Submitted to EPJ
Proteomic Analysis of the Acidocalcisome, an Organelle Conserved from Bacteria to Human Cells
Acidocalcisomes are acidic organelles present in a diverse range of organisms from bacteria to human cells. In this study acidocalcisomes were purified from the model organism Trypanosoma brucei, and their protein composition was determined by mass spectrometry. The results, along with those that we previously reported, show that acidocalcisomes are rich in pumps and transporters, involved in phosphate and cation homeostasis, and calcium signaling. We validated the acidocalcisome localization of seven new, putative, acidocalcisome proteins (phosphate transporter, vacuolar H+-ATPase subunits a and d, vacuolar iron transporter, zinc transporter, polyamine transporter, and acid phosphatase), confirmed the presence of six previously characterized acidocalcisome proteins, and validated the localization of five novel proteins to different subcellular compartments by expressing them fused to epitope tags in their endogenous loci or by immunofluorescence microscopy with specific antibodies. Knockdown of several newly identified acidocalcisome proteins by RNA interference (RNAi) revealed that they are essential for the survival of the parasites. These results provide a comprehensive insight into the unique composition of acidocalcisomes of T. brucei, an important eukaryotic pathogen, and direct evidence that acidocalcisomes are especially adapted for the accumulation of polyphosphate
The Third wave in globalization theory
This essay examines a proposition made in the literature that there are three waves in globalization theoryâthe globalist, skeptical, and postskeptical or transformational wavesâand argues that this division requires a new look. The essay is a critique of the third of these waves and its relationship with the second wave. Contributors to the third wave not only defend the idea of globalization from criticism by the skeptics but also try to construct a more complex and qualified theory of globalization than provided by first-wave accounts. The argument made here is that third-wave authors come to conclusions that try to defend globalization yet include qualifications that in practice reaffirm skeptical claims. This feature of the literature has been overlooked in debates and the aim of this essay is to revisit the literature and identify as well as discuss this problem. Such a presentation has political implications. Third wavers propose globalist cosmopolitan democracy when the substance of their arguments does more in practice to bolster the skeptical view of politics based on inequality and conflict, nation-states and regional blocs, and alliances of common interest or ideology rather than cosmopolitan global structures
On Eisenbud's and Wigner's R-matrix: A general approach
The main objective of this paper is to give a rigorous treatment of Wigner's
and Eisenbud's -matrix method for scattering matrices of scattering systems
consisting of two selfadjoint extensions of the same symmetric operator with
finite deficiency indices. In the framework of boundary triplets and associated
Weyl functions an abstract generalization of the -matrix method is developed
and the results are applied to Schr\"odinger operators on the real axis
The Association of NonâDrug-Related Pavlovian-to-Instrumental Transfer Effect in Nucleus Accumbens With Relapse in Alcohol Dependence: A Replication
BACKGROUND: The Pavlovian-to-instrumental transfer (PIT) paradigm measures the effects of Pavlovian conditioned cues on instrumental behavior in the laboratory. A previous study conducted by our research group observed activity in the left nucleus accumbens (NAcc) elicited by a nonâdrug-related PIT task across patients with alcohol dependence (AD) and healthy control subjects, and the left NAcc PIT effect differentiated patients who subsequently relapsed from those who remained abstinent. In this study, we aimed to examine whether such effects were present in a larger sample collected at a later date.
METHODS: A total of 129 recently detoxified patients with AD (21 females) and 74 healthy, age- and gender-matched control subjects (12 females) performing a PIT task during functional magnetic resonance imaging were examined. After task assessments, patients were followed for 6 months. Forty-seven patients relapsed and 37 remained abstinent.
RESULTS: We found a significant behavioral nonâdrug-related PIT effect and PIT-related activity in the NAcc across all participants. Moreover, subsequent relapsers showed stronger behavioral and left NAcc PIT effects than abstainers. These findings are consistent with our previous findings.
CONCLUSIONS: Behavioral nonâdrug-related PIT and neural PIT correlates are associated with prospective relapse risk in AD. This study replicated previous findings and provides evidence for the clinical relevance of PIT mechanisms to treatment outcome in AD. The observed difference between prospective relapsers and abstainers in the NAcc PIT effect in our study is small overall. Future studies are needed to further elucidate the mechanisms and the possible modulators of neural PIT in relapse in AD
Field-induced effects in the spin liquid candidate PbCuTeO
PbCuTeO is considered as one of the rare candidate materials for a
three-dimensional quantum spin liquid (QSL). This assessment was based on the
results of various magnetic experiments, performed mainly on polycrystalline
material. More recent measurements on single crystals revealed an even more
exotic behavior, yielding ferroelectric order below , accompanied by distinct lattice distortions, and a somewhat
modified magnetic response which is still consistent with a QSL. Here we report
on low-temperature measurements of various thermodynamic, magnetic and
dielectric properties of single crystalline PbCuTeO in magnetic fields
. The combination of these various probes allows us to
construct a detailed - phase diagram including a ferroelectric phase for
and a -induced magnetic phase at
. These phases are preceded by or coincide with a structural
transition from a cubic high-temperature phase into a distorted non-cubic
low-temperature state. The phase diagram discloses two quantum critical points
(QCPs) in the accessible field range, a ferroelectric QCP at =
and a magnetic QCP at = . Field-induced
lattice distortions, observed in the state at and which are
assigned to the effect of spin-orbit interaction of the Cu-ions, are
considered as the key mechanism by which the magnetic field couples to the
dielectric degrees of freedom in this material
Stronger Prejudices Are Associated With Decreased Model-Based Control
Background: Prejudices against minorities can be understood as habitually negative evaluations that are kept in spite of evidence to the contrary. Therefore, individuals with strong prejudices might be dominated by habitual or âautomaticâ reactions at the expense of more controlled reactions. Computational theories suggest individual differences in the balance between habitual/model-free and deliberative/model-based decision-making.
Methods: 127 subjects performed the two Step task and completed the blatant and subtle prejudice scale.
Results: By using analyses of choices and reaction times in combination with computational modeling, subjects with stronger blatant prejudices showed a shift away from model-based control. There was no association between these decision-making processes and subtle prejudices.
Conclusion: These results support the idea that blatant prejudices toward minorities are related to a relative dominance of habitual decision-making. This finding has important implications for developing interventions that target to change prejudices across societies
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